DENVER—Marijuana magazines are under scrutiny in Colorado, where lawmakers might require stores to put them behind the counter.

The unusual provision to treat pot magazines like pornography was considered Thursday in a Senate committee. If approved, the provision would make Colorado the first state to require stores that allow entry to shoppers under age 21 to place pot magazines behind the counter.

“It’s analogous to the pornography example,” said Republican Rep. Bob Gardner, sponsor of the magazine amendment.

The Senate committee, considering a marijuana regulation bill, delayed a vote on the magazine requirement. A decision was expected Friday on the proposal, which was added in a late-night amendment last week and caught Senate sponsors by surprise.

“I’m not really sure what that whole thing means,” conceded the sponsor of the bill, Democratic Sen. Cheri Jahn.

The magazine restriction faces long odds in the Legislature, though. Gardner conceded Thursday that he wouldn’t be surprised if his magazine idea fails to make the final marijuana regulation bill.

A lawyer for High Times magazine called the magazine restriction “patently unconstitutional” and said there’s no legal precedent for treating pictures of a drug as obscene. Lawyer David Holland said the magazine would likely sue if the provision becomes law.

“It is a content-based restriction that violates freedom of speech,” Holland said.

The magazine provision was among a long list of pot regulations awaiting a vote in the Senate Finance Committee on Thursday. The bill also includes labeling and packaging requirements, and limits retail sales to out-of-state customers to 0.25 ounce in a single transaction, though all adults would be allowed to possess a full ounce of the drug.

Colorado and Washington, the two states that voted last year to flout federal drug law and allow pot for recreational use by adults over 21, are still awaiting a federal response. In the meantime, the states are on their own regulating the drug. Colorado’s Legislature is considering at least three separate bills to dictate how pot should be grown, packaged, sold and taxed.

Gardner insisted his magazine limit should be included in Colorado’s final pot regulation. He said many marijuana magazines should be considered commercial speech, like advertisements for the drug, and therefore subject to increased state regulation.

“As we legalize marijuana, I think we can also control—in time place and manner—how it is advertised. I think that it’s constitutionally defensible,” Gardner said.